Short-wave directional radio communication system



June 9, 1953 E. B'. BARTELINK SHORT-WAVE DIRECTIONAL RADIO COMMUNICATION SYSTEMV Filed Nov. 22, 1950 2 Sheets-Sheet v1 mvsN-roe. Evenzo-Aveo H.B. BARreLuNK.

BY 0u/ ATTORNEY;

June 9,' 1953 E. H. B. BARTELINK 2,641,755

SHORT-WAVE DIRECTIONAL RADIO COMMUNICATION SYSTEM Filed Nov. 22. 195o 2 sheets-sheet 2 EVERHAARD FLB. BAzvELnNK.

ATTO R N EYS Patented June 9, 1953 SHORT-WAVE DIREf/"IIOJLL` RADIO Y COMMUNICATION SYS-TEM Everhard H. B. Bartelink, Bronxville, N. Y., as-

signor, by mesneassignments, to Automatic Electric Laboratories, Inc., Chicago, Ill., a corporation ofDelaware Application November 22, 1950, Serial No. 197,101

i 2o anims. 1

This invention pertains to short-wave, directional radio communication systems, and more particularly to a radio telephone system comprising a central olice and outlying stations, operating'on extremely short wave-lengths for beaming the radio waves between the central olce and the various outlying or subscribers stations. The outlying stations may have xed locations, such as in the homes of telephone subscribers, or may be mounted on moving objects, such as automobiles, planes, trains, etc.

The invention, in accordance with one of its modifications, is especially adaptedl for providing telephone service in sparsely settled regions where the cost ofY providing telephone lines from a central oni-ce to the various subscribers homes becomes prohibitive. Under such circumstances, microwave radio transmission provides a feasible solution. By the use of microwaves, i. e., radio waves of, for example, about three to fty centimeters, more or less, sharplyv delineated beams of radio energy may be directed along rectilinear paths between the central office and the individual stations, thereby to provide privacy of communication in a relatively cheap and eilicient manner.

For beaming the microwaves to individual outlying stations having xed locations, the central oiilce might be provided vwith an equal number of directive aerials individually" so mounted as to transmit to and receive from the individual outlying stations respectively. This arrangement would be cumbersome, complicated and unduly expensive. Another possibility would be to employ at the central ofce a fewer number of directive aerials so mounted about a common axis as to serve successive sectors of the area about the central oilice comprising in aggregate all directions of the compass as viewed therefrom. This proposal is objectionable in that transmission and reception are non-uniform over any given sector being Vbest along the median line thereof and least along the edges. Also stations located along the fringes of a sector are subject to interference or cross-talk from the adjacent sector.

In accordance with the present invention, I propose to overcome the above-noted objections by providing the central oiice with a normally rotating directive antenna system and associated radio transmitting and receiving equip ment adapted to provide a radio link to any of the outlying stations, it being understood that thislink can serve only one outlying station at a time. It will also be understood that lf traic conditions Warrant, additional radio links of a similar character may be provided as explained hereinafter, Hence the operation of only one link will be explained for the moment.

Each outlying or subscribers station is provided with a normally operating radio receiver and a normally inoperative radio transmitter, to which the subscribers telephone set is connected. The radio transmitter and receiver units extend to a directive antenna system directed toward the central olce. During periods when the system ls not in use, the central office antenna rotates continuously at the rate of a few seconds tion of the calling station until the subscriber hangs up. The operator thereupon connects her telephone set to the central oilice radio transmitting and receiving equipment to switch on the transmitter, the receiver being continuously operating. The radio channel or link is now in condition for carrying on a two-way conversation between the calling subscriber and the operator. If the subscriber desires a long distance or local wire connection, the operator completes the call in the usual way. At the conclusion of the call, the subscriber hangs up, his transmitter is thereby cut olf, and the central oice carrier relay released to start the antenna rotating again. When the operator disconnects, the central oice transmitter is also out ofi.

In order to provide means for the operator to originate a` call to any of the outlying stations, there are disposed about the rotating antenna shaft, a plurality of stationary contacts individually positoned in the radial directions of the outlying stations respectively. As the antenna shaft rotates, a contact arm mounted thereon sweeps over these contacts successively. The operator is provided with a dial switch having xed contacts arranged in conformity with the fixed contacts disposed about the antenna shaft and Wired thereto respectively. The dial switch is provided with a manually rotatable switch arm adapted to contact the fixed contacts thereof successively.

In order to originate a call to an outlying station, the operator rotates the contact arm of the dial switch to the fixed contact corresponding to the station desired and connects her telephone set to the central oice radio ltransmitting and receiving equipment. As the antenna shaft rotates, the contact arm thereon will ultimately engage the associated fixed contact thereof,

which is wired to the fixed contact at which the jl rection of the station to be called. The operator thereupon applies a suitable source of ringing` current, such as a periodically interrupted, high frequency, modulating current, to the central ofce radio transmitter, whereby the so-modulated carrier wave beamed tothe called station, rings the subscriber who answers in the usual .manner. At the conclusion of the call, the operator disconnects and the subscriber hangs up, thereby to close the control circuit for again initiating rotation of the antenna, which continues to rotate until a new call is placed.

. In accordance with another modification of the invention, the central oflice antenna is provided with additional means for automatically tracking moving objects, whereby two-way, microwave, radio telephone service may be carried on between the central office and remote stations mounted in moving objects, such as automobiles, trains, planes, etc., this modification being also adapted for automatically aligning the central ofce antenna with the precise direction of a remote station during communication therewith, whether such station has a fixed or moving location.

Having thus described the invention in general terms, reference will now be had to the accompanying drawings for a more detailed description, wherein: y

Fig. l illustrates more or less schematically and diagrammatically the modification of the invention first above described, for effecting microwave radio communication between the central oiiice and outlying stations having fixed v locations.

Fig. 2 illustrates in similar fashion the central office antenna system and appurtenant appara- Y tus and circuits, as modified for automatically tracking outlying stations mounted on moving objects and employing to this end a dual lobe directive antenna as part of the automatic tracking equipment; while Fig. 3 is a graphical represpectively to inner and outer, preferably concentric conductors Il), I I, extending axially down the interior of the antenna shaft I. Similarly, the halves of dipole 9 are connected respectively Vto concentric conductors II, I2. The concentric conductors extend the length of the antenna shaft and project beyond the base thereof, as at It, and thence into a rotatable concentric conductor joint I5, the latter being illustrated vdiagrammatically since joints of this type are =well known. From the rotating joint I5, a concentric conductor connection extends to the out- :put of a microwave radio transmitter I6, while another similar connection extends to the input of a microwave radio receiver Il. It will be understood that transmitter I5 is thus connected to conductors Ill, II extending to the transmitting antenna Il; while receiver Il is connected to conductors II, I2 extending to the receiving antenna 5.

vThe inputy to transmitter I6 and the output of receiver Il are connected to conductors I8 through a hybrid coil I9 in the conventional manner for minimizing reradiation of received signals, conductors I8 in turn terminating in a jack I9 on the operators switchboard. Jack I9 is adapted to receive a corresponding plug 20 of an operator-s cord circuit and associated telephone set, shown generally at 2 I.

The antenna shaft I is provided near its lower end with a metal collar 22 having integral therewith a horizontally extending switch arm 23 adapted, during rotation of shaft I, to sweep across and successively engagea series of stathe dial switch are wired to the corresponding resentation of the dual lobe arrangement of the aforesaid antenna array.

Referring now to Fig. l, there is shown at I a vertically disposed shaft, of insulating material, adapted to be continuously rotated above its axis by means of a motor 2 geared to the antenna shaft through worm and pinion gearing 3, thereby to impart to shaft I, continuous rotation at the rate of a few seconds per revolution. Shaft I is of course mounted in suitable bearings, preferably ball or roller bearings, which, however, have lbeen omitted for simplicity of illustration. The shaft I may be mounted at any convenient location at the central oiiice, for example, upon the roof thereof.

Rigidly secured to the shaft in vertical alignment are a pair of directional transmitting and receiving antennas 4, 5, each comprising preferably a parabolically shaped metal dish, such as 6, l, made of" aluminum or the like, at the focus of which is mounted a dipole antenna, such asS, 9. The halves of the dipole 8 are connected contacts about the antenna shaft by means of the connections, such as 2l. The dial switch 25 is provided with a manually rotatable knob having secured theretoa rotatable switch arm 28 adapted tov engage the stationary contacts thereof successively, as the knob is rotated.

Associated with jack I9 is a switch 29, actuated upon `insertion of plug 20 into the jack. Switch 29 is provided with a lower set ofcontacts for applying ground, as shown, to the radio transmitter IG upon insertion of the plug 20 into the jack I9, thereby to energize the transmitter. Switch 2S is also provided with a pair of upper contacts for applying, as shown, a grounded battery to the rotatable arm 28 of the dial switch 25 upon insertion of the plug into the jack. Bearing against the metal collar 22 carried by shaft I, is a wiping brush from which a connection extends through a relay 30 to ground as shown. y

rlhe electrical motor 2 which rotates the antenna shaft I, as abovey explained, is normally energized over a pair of leads 3l, 32 from a power supply connected to terminals 33. The input connection 3lV to thevmotor is wired through normally closed lback contacts of relay 30, and is also wired in series therewith through normally closed back contacts of a carrier-actuated relay 34, connected to the radio receiver as explained hereinafter.

x. Disposed about the central oflice at various distances and in various directions therefrom aref a series of subscribers stations, as indicated by stations A to F inc., these stations being individually disposed in directions from the central oiiice corresponding to the dispositions of the stationary contacts 24 mounted about the antenna shaft I at the central office.

Y radio transmitterT tothe central oiice receiving antenna 5. Similarly, the -input to the radio receiver R is connected to a directive aerial 36,

so positioned as to receive radio energy beamed thereto from the radio transmitting antenna 4 at the central oce.

The output of the radio receiver R is connected over leads 31 to the telephone receiver 38, normally positioned on the switch hook 39 of the telephone set. The subscribers microphone transmitter 49 is coupled to the input of the radio transmitter T through a two-winding, isolating transformer 40a, the primary circuit of which includes a battery 4I having its negative terminal grounded as at 42, which primary circuit is closed at the switch hook contacts 43 to energize the microphone transmitter upon removal of the receiver from the switch hook. The switch hook is provided with an additional, normally open contact connected over a lead 44 to the radio transmitter T, for switching on the transmitter upon removal of the receiver from the switch hook, this being accomplished by the connection of the ground 42 to lead 44 through `the switch hook contacts upon removal of the receiver from the switch hook. For purposes of ringing the station, the circuit of the radio receiver R includes a carrier-actuated relay 45, which relay controls, through its contacts, a local circuit 4E for operating a buzzer or bell from battery 4I as shown.

In the operation of the system, the radio receiver Il at the central cnice, and those at the various subscriber stations, such as receiver R at station A, are normally in operation. Also the antenna shaft I is normally being rotated by motor 2 to cause the central oftlce antennas 4, 5 `continuously to sweep around in the directions of the various subscriber station successively. Assuming now that a subscriber, such as station A, desires to call the central oce, the subscriber will remove his receiver 36 from the switch hook,

`thereby completing the circuit to ground at 42 over connecetion 44 to energize the subscribers radio transmitter 35. Energzation of the transmitter will cause carrier wave energy to be beamen from the subscribers transmitting antenna 35 in the direction of the central oflice. As the antenna shaft swings around to point its antennas in the direction of the calling station, the receiving antenna 5 will pick up the carrier wave being beamed from the subscribers transmitting antenna and transmit the same to the central oihce radio receiver I1, thereby to operate the carrier-actuated relay 34. Operation of this relay accomplishes two things. First, it opens at its contacts 47 the power supply circuit for motor 2, thereby stopping the motor and with it the antenna shaft, so that the shaft is brought to rest with its antennas 4, 5 pointing in the direction of the calling station. Operation `of relay 34l alsok closes, through its left front contacts, a signalling circuit 48 to signal the operator.

The opera-tor thereupon inserts the plug 2U of her cord circuit into jack I9'. Switch 29 is thereby actuated to apply ground to the radio transmitter I6 and thus energize the transmitter. The operator thereupon actuates key 49 of her cord circuit to the right to connect her telephone set 5D to the radio transmitting andl receiving equipment I6, I1 over the cord circuit. If the calling station seeks a long-distance or further connec tion over a metallic line, the operator completes the call inl the usual way by plugging her back cord 5I' into an appropriate jackV and ringing,

At the conclusion of the call, the subscriber hangs up, thereby cutting oi his transmitter at the contacts of his receiver switch as above explained. This terminates the transmission of carrier from his station to the central office, thereby causing the carrier-actuated relay 34 thereat to release. Similarly, when the operator removes plug 2U from jack I9, the central oiice transmitter I6 is cut oif by the opening of the lower contacts of switch 29, thus terminating the transmission of carrier energy from the central oice to the calling station. The release of relay 34 closes the power supply circuit for motor 2, whereby the central oilce antenna starts rotating antenna starts rotating and searching again.

Assume now that the central office desires to initiate a call to one of the subscriber stations, suchv as station A. The operator adjusts the dial switch 25 until its switch arm 28 engages the contact, such as A, corresponding to station A` to be called. The operator thereupon inserts plug 20 into jack I9 to switch on the central oice transmitter, as explained, and also operates switch 29 to connect the battery to the switch arm of the dial switch. Meantime, the antenna wil continue to rotate until switch arm 23 thereof engages contact A corresponding to the station selected. Thereupon relay 30 will operate to open the power circuit of motor 2, thereby bringing the motor and antenna shaft to rest with the antennas 4, 5 pointing in the direction of station A. Short-wave radio energy will now be beamed from the central oice transmitting antenna 4 to the selected subscriber station, and will be picked up by his receiving antenna 36 thereat. This will pull up the carrier relay 45 which will thereafter rapidly operate and release in response to ringing by the central oiiice operator, and thus actuate the bell or buzzer in the local subscribers ringing circuit 46. When the subscriber answers by removing his receiver 38 from the switch hook, his radio transmitter is energized, as explained, and the system is thereupon operable for carrying on communication between the subscriber and the central oice operator.

At the conclusion of the call, the subscriber hangs up, thereby cutting off his transmitter, thus releasing the carrier relay 34 at the central oilice as explained. Also, the central oice operator disconnects her cord 20 from jack I9, thus releasing relay 30 at the central ofce. This closes the motor circuit starting the antenna rotating and searching again. It should be pointed out. in this connection, that the motor will not start rotating until both the subscriber hangs up and the operator disconnects, by reasonl of the fact that the motor power supply circuit is under control of relays 30 and 34 in series, the operation of relay 30 being under the operators control, and the operation of relay 34 being under the subscribers control, as above explained.

The 'central oce apparatus above described can of course be duplicated to the extent required to meet trac conditions, in the event that traf- -c is suciently heavy that one rotating aerial can not handle all calls without undue delay.

Referring to the automatic tracking antenna system of Fig. 2, components which are the same as in Fig. 1 are similarly designated and hence require no further description. In this modilcation, the antenna shaft l, in addition to mounting the vertically aligned transmitting and receiving antennas lli, 5, also mounts a pair of horizontally spaced, directional antennas B0, l, carried by a cross-arm 62, this being the dual lobe antennas employed for the automatic tracklng.

Antennas 6e, 6l are connected over coaxial lines, similar to lil-l2, Fig. 1, to the rotating joint i5, from whence coaxial lines S3, 62 connect these antennas respectively to a pair of amplifier-rectifier units 5, 66, the rectied outputs of which are oppositely applied to the opposite halves of a balanced amplifier 61. This amplifier contains a pair of ampliiier tubes 68, 69, connected push-pull as shown, the plate circuits of which contain respectively the shunt field windings 1G, 'H of an reversible motor l2, the armature i3 of which is mounted on the same shaft as that of the antenna search motor 2, as

shown.

The plate circuits of tubes 68, 69 are energized from a battery 'M contained in the common plate current return lead l5 of amplifier 61, this platelead 'i5 being wired through normally open upper contacts in multiple of relay 36 and 34, and

l thence to the midpoint between the shunt field windings l2, 'H of the reversible motor l2. The armature 'i3 of this motor is connected through one brush to the midpoint between its field windings '59, il, and through another brush to the negative side of battery '54, in consequence of which the reversible motor 2 is wholly deenergized so long as relays 30 and 34 are released, but is energized in the manner explained hereinafter, upon operation of either of these relays.

Now, as was explained above, in connection with Fig. 1, the Search motor 2 receives power from terminals 33 over a circuit traced through the back contacts of relays 3D and 32, so that motor 2 is continuously energized to rotate the antenna systemV for searching, k,during periods that the central oce system is idle. As soon, however, as an incoming or outgoing call is placed, either relay 3Q or 36's operates, as explained above, to open up the power supply circuit to motor 2, thereby to deenergize this motor and arrest the antenna system when pointing in the direction of the remote station to which a call is being placed.

As soon, however, as relay 3u or 3e operates to deenergize ythe search motor 2 as aforesaid, the operation of this relay closes, through its front contacts, the plate circuit above traced of the balanced amplifier 51, thereby to energize the armature of the reversible motor T2, the relative energizations of the iield windings 1Q, H of which,

' however, will depend on the relative signal inequal and opposite currents nowing through the Y eld windings l0, 'H of the reversible motor l2, in

consequence of which no rotative torque will be applied to the armature '13 thereof, in consequence of which the antenna system will remain stationary. If, however, the antenna system is not brought to rest pointing directly toward the remote station, one of the antennas' 6i), 6I will receive a stronger signal that the other, as a result of which the current in one or the motor iield windings T0, Il will be greater than in the other, the unbalanced current component being always in such direction as to rotate the armature 'i3 thereof in a direction to line the antenna system precisely with the direction of the remote station.

Should the remote"Y station be mounted on a mobile unit, such as an automobile, train, plane, etc.,the antenna system will locate and automatically track the remote station as it moves along, by operation of the antenna mechanism above described. The motion of the mobile unit will, in general, have a component transverse to the radial direction of the antenna system, which will tend continually to produce a greater signal intensity on one of the dual lobe antennas 6G, 6i thanon the other. In consequence, a correcting' unbalanced currentcomponent'will fiow in the motor eld windings 1li, 1I, in such direction as to energize the rotor T3 thereof in a direction to swing the antenna system into continual alignment with the moving object.

It will be observed that in the operation of the Fig. 2 system, motors 2 and 'Z2 can not be energized concurrently, inasmuch as one motor is energized through the back contacts of relays 36 and 3Q, while the other motor is energized through the front contacts thereof. Therefore, when relays 3b and 34 are released to energize motor 2 for searching, the rotor of the automatic tracking motor '2 merely idles around, the reverse being true when relay 32 or 34 is operated to energize motor i2 and concurrently to deenergize the search motor 2. Fig. 3 is a view looking down from above on the horizontallyfspaced, automatic tracking antennas 60, 6i of Fig. 2, the dashed lines 16, 'Il of Fig. 3 graphically depicting the lobes or field intensity or sensitivity patterns of these antennas respectively during transmission o1' reception. It will be observed that antennas 6G, 6l are not mounted with their axes parallel, but rather with their axes slightly diverging to spread the lobes as indicated. The purpose of this is to enhance the diierence component between the signal intensities received by the two antennas respectively, whenv the antenna system is off-target from the true direction of the remote station. Thus, assuming the remote station to be at 1B, the signal intensity diierence component on thetwo antennas for swinging the antenna system in alignment with the station at i8 is indicated by the full line 19. Similarly, the lobe diiierence, correcting component would result i1" the remote station were in the direction 8|. However, when the remote station is in precise alignment with the antenna system, as at 32, the lobe difference component will reduce lto zero, as indicated at 83, so that no further correction will be vapplied to the antenna adjustment.

The mobile units may of course-be equipped with automatic tracking antenna systems, generally similar to Fig. 2, but this would be uneconomical. A preferred arrangement is to equip the mobile units with stationary antennas of the so-called pancake lobe type, i. e., those whichreceive and transmit equally well in all 9 horizontal directions, :but which have relatively small components in the vertical direction. Antennas of this character are well known and hence require no detailed description or illustration herein. By mounting on the mobile units, transmitting and receiving antennas of this character in substantially axial alignment but vertically spaced from each other, their resulting lobes will be vertically spaced at the mobile unit, thereby to isolate the radio transmitting and receiving channels thereat, thus to prevent feedback from the transmitter into the receiver of the mobile unit.

Reverting to Fig. l, the switch arm and contact arrangements 23, 24 and 26, 28, for directing the aerial toward a called station, can of course be replaced by a selsyn motor arrangement. in which event only the fixed contacts 24 and the rotating switch arm 23 would be retained about the antenna shaft. This `modifica-- tion would provide increased ilexibility ofpreselection and direction of the antenna, inasmuch as the operator could thereby direct the antenna toward any point in the compass, with reference to a graduated dial on the selsyn motor control unit.

I claim:

`1. A short-wave radio communication system comprising a central cnice and a plurality of stations remotely disposed thereabout, each equipped with radio transmitter .and receiver; a directional antenna system rotatably mounted at the central office to scan said stations successively during rotation; means for continuously rotating said antenna preparatory to the transmission of a carrier wave from one of said stations; and means at said central office responsive to a carrier wave transmitted from any one of said tral oilice thereto; a Vdirectional antenna systemA rotatably Amounted ,at the central oee for scanning saidstations successively during rotation; means for continuously rotating said antenna preparatory to the transmission of 1a radio beam fromone of said stations; and means including a `relay at the central office responsiveA to a radiobeam transmitted from any one of `said stations for arresting the antenna rotation with the antenna pointing toward said station, and for thereafter releasing said antenna to resume continuous `rotation thereof upon termination of said radio beam transmission.

3. A short-wave radio telephone system com-v prising a central oilce and a plurality of stations remotely disposed thereabout, each equippedwith a normally energized radio receiver and a normally deenergized radio transmitter; a directional antenna -at each station positioned to direct toward the central `office a radio beam transmitted therefrom and to receive a radio beam directed `from the central oiice thereto; a telephoneset `at each station connected to the `radio transmitter and receiver thereat, said setincluding a switch for energizing the associated radio from any one of said stations for arresting theantenna rotation with the antenna pointing to said station, and for concurrently signalling at the central oiice; a telephone set at the central oiiice; and means for connecting said set to the radio transmitter and receiver thereat, thereby to energize the transmitter for effecting two-way communication between the central office and the said station.

fl. A short-wave radio communication system comprising a central oiilce and a plurality of stations remotely disposed thereabout, each equipped with radio transmitter and receiver; a directional antenna rotatably mounted at the central oice for scanning said stations successively during rotation; means for continuously rotating said antenna preparatory to the initiation of a call from any one of said stations; and means at the central oilice operating responsive to the initiation of a call fromany one of said stations `for automatically arresting said central oce antenna rotation, with the antenna thereof pointing to said one of said plurality of stations initiating a call.

5. A short-wave radio communication system comprising a central omce and a plurality of stations ,remotely disposed thereabout, each equipped with radio transmitter and receiver; a directional antenna rotatably mounted at the central oiiice for scanning said stations successively during rotation; means for continuously rotating said antenna preparatory to the initiation of a call from said central oiiice to any of said stations; and means at the central office responsive to the initiation of a call from said central oice to any of said stations for automatically arresting saidcentral oice antenna rotation, with the antenna thereof vpointing to a preselected one of said plurality of stations, said second means including a disabling circuit for said irst means, said disabling circuit comprising a plurality of contacts disposed about said rotatable antenna in the radial directions of said stations respectively, and Va switch arm rotatable kby and with said antenna `for engaging said contacts suc-V cessively during rotation for completing said disabling circuit.

.6. A vshort--wave radio communication system comprising `a 'central ofce and a-plurality of stations remotely disposed thereabout, each equipped with radio transmitter and receiver; a

directional antennaat each station positioned.

to direct toward the central oice a radio beam transmitted therefrom; an antenna at -the central oiice rotatably mounted to scan said stations successively during rotation;V means for continuously rotating said antenna preparatory to the transmission of a radio beam from any one of said stations and preparatory to the initiation of a call from `said central oiiice to any one of said stations; means including said rotating antenna and a relay at the central office, responsive to a radio beam Atransmitted from any one of said stationsfor arresting said central oilce antenna rotation, with the ,antenna thereof pointing toward .Saidstatilm land for lreleasing said antenna to resume rotation upon cessation of said radiol beam transmitted from said station; and means at the central office for automatically arresting said central cnice antenna rotation upon the initiation of a call from said central oiiice, with the antenna thereof pointing to any preselectedV transmitted therefrom; an antenna at the central oice rotatably mounted to scan said stations successively during rotation; means for continuouslyrotating said antenna preparatory to the transmission of a radio beamv from any one of said stations and preparatory to the initiation of a call from said central oice to any one of lsaid stations; means including said rotatable antenna and a relay at the central oiice, responsive to a radio beam transmitted from any one of said stations for a-rresting said central office antenna rotation, with the antenna thereof pointing toward said station, and for releasing said antenna to resume rotation upon cessation of said radio beam transmitted from said station; and means at the central office for automatically arresting said central Voffice antenna rotation, with the antenna thereofpointing to any preselected station of said plurality, said last-*named means including a disabling circuit for said first means, said disabling circuit including fixed contacts disposed about said rotatingantenna in the radial directions of said stations respectively, together with a switch arm carried by and rotating with said antenna for engaging said contacts successively fol completing said disabling circuit.

8. In a short-Wave radio communication system: a rotatably mounted directional antenna adapted for searching and establishing communication With xed and mobile remote stations; `means at said antenna for continuously rotating said antenna preparatory to the transmission of a signal from one of said remote stations;l means responsive to signals received from one of said remote stations for automatically stopping the antenna when directed thereto; and means for thereafter causing said antenna automatically to follow said remote station if mobile', so llong as from oneof said remote stations; means including a relay responsive to signals picked up'by said antenna from one of said remote stations for automatically stopping the antenna When directed thereto; and Vmeans for thereafter causing said antenna automatically to follow` the direction of said remote station, if moving, so long as signals are received therefrom.

10. In a short-Wave radio communication system: a rotatably mounted directional antenna automatically stopping the antenna when 'di-v rected thereto; land means including said antenna, a balanced ampliner and a reversible motor responsive thereto, for causing said antenna thereafter automatically to follow the directionv of said remote station if mobile, so long as sign nals `are received therefrom. f

l1. In a short-Wave radio communication sys-V tem: a rotatably mounted directional antenna adapted for searching and establishing communication With fixed and mobile remote stations;

means for continuously rotating said antennav preparatory to the transmission of signals from one of said remote stations and preparatory to the initiation of a call from said rotating antenna; means including a rst relay for stopping said antenna When pointing in any pre-' selected direction for calling one of said remote stations; means including a second relay re' sponsive to signals picked up by said antenna y nals from one of said remote stationsrand preadapted for searching and establishing communication with xed and mobile remote stations; means for continuously rotating said antenna preparatory to the transmission of signals from one of said remote stations; means including a relay responsive to signals picked up by said antenna from one of said remote stations for paratory to the initiation of a call from saidY rotating antenna; means including a rst relay for stopping said antenna when pointing in any preselected direction for calling one of said remote stations; means including a second relay responsive to signals picked up by said antenna from one of said remote stations for stopping the antenna when directed thereto; and means Vincluding said antenna, a balanced amplifier anda reversible motor for causing said antenna thereafter automatically to follow the direction oi said station if mobile during signal reception therefrom. I I

13.' In a 'short-Wave radio communication system: a rotatably mounted antenna shaft; direcl stations; means continuously rotating said antenna preparatory to the transmission of signals from one' of said remote stations; means including a relay responsive to signals picked up by said antenna means for stopping said antenna rotation when directed thereto; and means including a pair of horizontally spaced directional antennas carried by said shaft,y a balanced amplifier and a reversible motor responsive thereto,

for causing said antenna thereafter automatically to follow the 'direction of said station.

14. In a short-Wave radio communication sys-V tem: a rotatably mounted antenna shaft; direcf tional antenna means mounted thereon for es-' tablishing communication with remote stations;

means for continuously rotating said antenna preparatory to the transmission of signals from i one of said remote stations and preparatory to the stopping of said antenna in a certain radial direction; means including lcontacts disposed about said shaft, a' switch arm carried thereby and a rst relay responsive thereto for stopping said shaftgrotation With saidantenna means pointing in the radial `direction of any said contact; and means including a second relay responsive to signals picked up by said antenna from lone of said remote stations for vstopping the antenna rotation when directed to said station.

15. In a short-wave radio communication system having -a central'oice and a plurality of stations remotely disposed thereabout, each of said stations having a transmitter and receiver, a directional antenna system rotatively mounted at the central oiiice,` said antenna system so mounted as to scan each of said stations successively as said antenna system is rotated, a mo- "tor coupled to said antenna system for continuously rotating saidantenna system preparatory tothe transmission of a carrier wave from one of said stations, an operating circuit for said motor whereby said motor operates to continuously rotate said antenna system, a radio receiver at said central ofiice connected to said antennasystem whereby Vsaid radio receiver at said central ofiicewill receive a carrier wave transmitted from one of said stations when said antenna system scans said one station, a relay associated with said radio receiver at said central oilice, saidrelay operated responsive to the reception by said radio receiver at the central oiiice of a carrier Wave from one of said stations, a first pair of contacts of said relay, said first pair of contacts connected in series in said operating circ-uit for said motor, said iirst pair of contacts closed when said relay is not operated, a second pair of contacts of said relay, `signalling means at said central oiiice for signalling the reception by the radio receiver at the central oiiice of a carrier wave from one of said stations, said second pair of contacts associated with. said signalling means whereby the operation of4 said second pair of contacts operates said signalling means, so that when said antenna system :scans one voil? said `stations transmitting a carrier wave said relay is operated to open said motor circuit `causing said antenna system to stop directed toward said station and is operated to signal said central office` 16, In a short-wave radio communication system having a central oiiice and a plurality of stations remotely disposed thereabout, each lof said stations having a transmitter and a receiver, a fixed directional transmitter antenna and a fixed directional receiver antenna mounted at each station and directed toward said central oiiice, a telephone at each station connected to said transmitter and receiver thereat, said receiver at each station continuously operating, sig- `nalling means associated with each of said continuously operating receivers operated responsive to the reception by said receivers of a carrier wave from said central office for signalling said station, a directional antenna system rotatively mounted at said 1central oiiice, said antenna system comprising a directional transmitter antennafand a directional receiver antenna, said i antenna system so mounted as to scan each of said stations successively as said Iantenna system is rotated, a motor coupled to said antenna system for continuously rotating said antenna system preparatory to the extension of a call from said central o'ice, an operating circuit for said motor whereby said motor operates to continuously rotate said antenna system, manual means at said central oiice for selecting one of said stations, means associated with said motor circuit operated responsive to said last mentioned means for breaking said operating circuit for said motor 4to cause said motor to stop thereby causing said antenna system to stop directed toward said selected station, a transmitter at said central oiice connected to said transmitter antenna mounted thereat, manual means for energizing said transmitter to cause a carrier wave to be transmitted from said transmitter antenna mounted thereat to said selected station, whereby said signalling means at said selected station is operated to signal said station.

17. In a system as claimed in claim 16, said rst means comprising a carrier operated relay, a ringing circuit including a pair of contacts of said carrier operated relay whereby the operation of said carrier operated relay completes said ringing circuit to signal said station and .manually operated means at said station for energizing said transmitter at said station whereby a modulated carrier wave is `transmitted from said station to said receiver antenna at said central office. Y

18. In a `system as claimed in claim 16, said second means' comprising a ring of` contacts, one of said contacts associated with` each of said stations, a'manually movable contact arm, said contact arm' rotatable to make contact successively with each of said ring of conta-cts, a second contact armmounted on said antenna system .there- -by rotating with said `antenna system, a second ring of .contacts disposed about said antenna, system so that as said antenna system rotates said second contact armsuccessively contacts said second ring of contacts', each of said second ring of contacts associated uwith one of said `stations Aand connected to the` comparable contacts of said rst ring of contacts, said third means comprising a relay, a pair of closed contacts of .said relay in series in said motor circuit, an operating circuit 'for said relay including said second contact arm, one of said contacts of said second ring of contacts associated with one of said stations, the comparable one of said contacts of said first ring of contacts, and said movable rst -contact arm, so that said first contact arm is moved to make contact with one of said contacts of said first ring of contacts to select one of said stations, whereby said operating circuit for said relay is completed when said second contact arm rotates to contact the contact of said second ring of contacts connected to the selected contact of said iirst ring of contacts, whereby said relay is operated to open its pair of contacts to break the 'operatingl circuit for said motor, to stop said motor, to cause said antenna system to stop directed toward said selected station.

. 19. In a short-wave communication system having a central office and a plurality of mobile stations remotely disposed thereabout, each of said stations having a transmitter and a receiver, directional antennas mounted on each mobile station and connected to the transmitter and receiver at each station for communication with said central oice, a directional antenna system rotatively mounted at said central cnice, said antenna system so mounted as to scan each of said stations successively as said antenna system is rotated, a motor coupled to said antenna system for continuously rotating said antenna vsystem preparatory to an extension of a call from said central oice and preparatory to the reception of a carrier wave from any one of said stations, an operating circuit for said motor whereby said motor operates to continuously rotate said antenna system, means at said central ofce for selecting one of said stations, means associated with said motor circuit operated responsive to said last mentioned means for breaking said operating circuit for said motor to cause said motor to stop thereby causing' said antenna system to 15 st op directed toward said selected station, means at said central voiiice 'associated with said rotating antenna system operated responsive to a carrier wave received by said rotating antenna sys tem from one of said stations to break said operating circuit for said motor to cause said motor tov stop thereby causing said antenna system to stop directed toward said selected station, a secv said last mentionedmeans onlyrwhen the operating circuit for saidfirst motorV is open whereby 'said' second motor :operates only after said rst motor has stopped, a pair of horizontally directionaly antennas mounted on said rotating antenna system to'rotate with said antenna system, said horizontally directional antennas oonnected to said balanced ampliersso that a ycarrier wave transmitted to said antenna system and received by said horizontally directional antennas will balance or unbalance said amplifiers to an extent dependent uponvthe direction from .which said carrier wave is received, said balanced amplifiers connected in the loperating circuit of said second motor tocause said motor to operateV in the direction which rotates said antenna lsystem to result in a directional alignment of said horizontally directional `antennas to said moving station to balance said amplifiers. 'f

20. In a short-wave communication system having a central voiiice and a plurality of mobile stations remotely disposed thereabout, an an tenna system rotatively mounted at said central cnice, said antenna system comprising a directional receiving antenna and a pair of horizontally spaced tracking antennas, said antenna sys-v tem so mounted as to scan each of said stations as said antenna system is rotated, a motor coupled said antenna system preparatory to the reception of a carrier wave from any one of said stations, an operating circuit for said motor whereby said motor operates to continuously rotate said an tenna system, means at said central office operated responsive to the reception by-said receiving antenna of a carrier wave from one of said stations when said station is scanned by said receiving antenna for breaking the operating circuit for said motor thereby causing said antenna system to stop directed toward said one station, a second motor coupled to said antenna system for rotating said antenna system as said one station is moved respective to said central office, a pair of balanced amplifiers, each of said ampliiers connected to include part of the eld windings ofvsaid second motor, said second motor being a reversable motor whereby said motor operates in eitherA direction dependent-upon the relative strength of the field windings, each of said amplifiers connected to one of said horizontally spaced tracking antennas so that said ampliers are relatively balanced and unbalanced dependent upon the Vdirection from which said carrier Wave is received, an operating circuit for said second motor, said operating circuit for said Isecond motor completed `by said means which breaks the operating circuit for said first motor whereby 'said second motor begins to operate when said rst motor stops, said second motor operating in a direction dependent upon the de- Y gree of unbalance between said ampliers.

EVERHARD H.l B. BARTELINK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,063,534; Wallace Dec. 8, 1936 2,152,329 SchuSSler Mar. 28, 1939 2,234,244 Gossel Mar. 11, 1941 2,257,319 Williams Sept. 30, 1941 2,401,759 Hersey June 11, 1946 2 550 '700 Lancor May l, 1951 

